A portion of a Joystiq article…
Unlike a computer mouse pointer which stops at the edge of the monitor, the Wii pointer completely disappears if the remote is not pointed directly at the screen area, even if it’s still well within the sensor bar’s range. What’s more, the system doesn’t even give any indication of where the missing cursor was last seen or which edge of the monitor it departed through.
It only takes a few seconds to get over the confusion and realign your remote, but it gets a little annoying when it happens multiple times in one play session. The problem is especially apparent when switching from gesture-based to pointer-based functions, such as transferring from sword-swinging to boomerang throwing in Zelda, or from racquet swinging to menu selection in Wii Sports: Tennis.
I am speaking for the entire GoNintendo staff when I say that the only time we have seen this happen is when we are leaving a Wii Sports game. Your hands are in different positions, and you aren’t made to point at the screen for them. When you quit, you have to point at the screen. That’s all there is to it.